1. The Field of the Invention
The present invention relates generally to windmills. More particularly, it concerns a wind turbine apparatus having overlapping sail members suitable for alternately catching the wind to turn a central cylinder and allowing the wind to pass, regardless of the wind direction.
2. The Background Art
Wind is among the oldest utilized energy sources. It has been known for centuries to build windmills and similar devices for catching the wind and converting the wind energy to mechanical energy in rotating windmill vanes. The kinetic energy in the rotating vanes was found to have many applications. It was initially used as a source of mechanical energy to drive various machinery such as grinders, water pumps, and so forth. As electrical energy developed into a popular energy source, it was discovered to intercouple a rotational gear system to the :rotating wheel base, and the gear system to an electrical generator. In this way, wind energy became convertible to electrical energy. This has motivated the development of a number of windmill systems and methods of harnessing the wind.
For example, U.S. Pat. No. 3,895,882 (issued Jul. 22, 1975 to Moyer) discloses a vertically disposed cylinder including a plurality of wind-engaging blades for inducing rotation of the cylinder about its vertical axis. Moyer's discovery, while effective in harnessing wind energy, has a number of disadvantages. The blades are not rotatable independent of the cylinder, such that each blade causes wind resistance against rotation of the cylinder about half of the time. The solution to this problem has been generally to add a moveable wind shield which blocks the wind from one side of the cylinder. The shield must be moved every time the wind changes direction, and thus requires significant operator attention. Since the wind often blows in multiple directions at a time, it is difficult to prevent wind resistance even with a shield. It is also difficult to disengage the device for resting, repair, and so forth. The power output of this type of windmill is limited by such disadvantages.
The Moyer patent is one of many patents directed to vertically disposed windmill structures. See, for example, U.S. Pat. Nos. 4,288,200 (issued on Sep. 8, 1981 to O'Hare), 4,278,896 (issued on Jul. 14, 1981 to McFarland), 4,260,325 (issued on Apr. 7, 1981 to Cymara), 1,810,113 (issued on Jun. 16, 1931 to Schlotzhauer), and 201,400 (issued Mar. 19, 1878 to Everhart). Each of these inventions relies of some kind of wind deflector, and the novelty of each generally subsists in the combination of the blade design therewith.
There is thus a need for a windmill device which can harness the wind without the need for a wind deflector, and which is easily disengageable.